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in Fig. 47. The sulphuric acid and alcohol are cautiously
mixed together in the distilling flask, which is then placed upon
a sand-bath and attached to the condenser. The mixture is
heated to 140 and alcohol is run in from the tap-funnel at the
same speed as the liquid distils (about three drops a second).
The temperature must be kept constant at 140145. When
about twice the quantity of alcohol contained in the original
mixture has been added and converted into ether, the distillation
is stopped. The receiver now contains, in addition to ether,
alcohol, water and sulphurous acid, The liquid is poured into

FIG. 47-
a large separating funnel and a small quantity (3040 c.c.) of
dilute caustic soda added and well shaken. After settling,
the caustic soda solution is drawn off below, and about the
same quantity of a strong solution of common salt added,
and the process of shaking and drawing off repeated. The
ether, which is now free from sulphurous acid and from
most of the alcohol, still contains water. It is therefore
poured into a large dry distilling flask and some pieces
of solid calcium chloride added. It is allowed to stand
loosely corked overnight. The distilling flask is now attached
to a long condenser and heated on the water-bath. The
ether, which distils, still contains traces of alcohol and water,
which it obstinately retains and from which it can only be freed